title: Presurgical connectome and postsurgical seizure control in temporal lobe epilepsy.
abstract: OBJECTIVE
  The objective of this study was to evaluate whether patients with surgically refractory medial temporal lobe epilepsy (MTLE) exhibit a distinct pattern of structural network organization involving the temporal lobes and extratemporal regions.
  
  
  METHODS
  We retrospectively studied 18 healthy controls and 20 patients with medication refractory unilateral MTLE who underwent anterior temporal lobectomy for treatment of seizures. Patients were classified as seizure-free or not seizure-free at least 1 year after surgery. The presurgical brain connectome was calculated through probabilistic connectivity from MRI-diffusion tensor imaging from 83 anatomically defined regions of interest encompassing the whole brain. The connectivity patterns were analyzed regarding group differences in regional connectivity and network graph properties.
  
  
  RESULTS
  Compared with controls, patients exhibited a decrease in connectivity involving ipsilateral thalamocortical regions, with a pathologic increase in ipsilateral medial temporal lobe, insular, and frontal connectivity. Among patients, those not seizure-free exhibited a higher connectivity between structures in 1) the ipsilateral medial and lateral temporal lobe, 2) the ipsilateral medial temporal and parietal lobe, and 3) the contralateral temporal pole and parietal lobe. Patients not seizure-free also exhibited lower small-worldness in the subnetwork within the ipsilateral temporal lobe, with higher subnetwork integration at the expense of segregation.
  
  
  CONCLUSIONS
  MTLE is associated with network rearrangement within, but not restricted to, the temporal lobe ipsilateral to the onset of seizures. Networks involving key components of the medial temporal lobe and structures traditionally not removed during surgery may be associated with seizure control after surgical treatment of MTLE.
authors.affiliation: From the Comprehensive Epilepsy Center, Department of Neurosciences (L.B., R.S., T.N., J.C.E.), Department of Radiology and Radiological Science (J.A.H., A.T.), and Center for Biomedical Imaging (L.B., J.A.H., A.T.), Medical University of South Carolina, Charleston; and Department of Neurosurgery (S.S.G.), Straub Clinic & Hospital, Honolulu, HI.
authors.forename: Leonardo
authors.initials: L
authors.lastname: Bonilha
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Helpern
authors.forename: Rup
authors.initials: R
authors.lastname: Sainju
authors.forename: Travis
authors.initials: T
authors.lastname: Nesland
authors.forename: Jonathan C
authors.initials: JC
authors.lastname: Edwards
authors.forename: Steven S
authors.initials: SS
authors.lastname: Glazier
authors.forename: Ali
authors.initials: A
authors.lastname: Tabesh
mesh_terms: D000328:Adult; D038481:Anterior Temporal Lobectomy / Q000379:methods*; D063132:Connectome / Q000379:methods* / Q000451:nursing*; D004569:Electroencephalography; D004833:Epilepsy, Temporal Lobe / Q000473:pathology* / Q000503:physiopathology / Q000601:surgery*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009434:Neural Pathways / Q000473:pathology; D012189:Retrospective Studies